JPH0654124A - Image reader and chart for variable power/focus detection to be used for image reader - Google Patents

Abstract

PURPOSE:To enable the acquisition of plural variable powers even with a single lens by driving the lens and an optical path changing means and setting a magnification based on a command. CONSTITUTION:After an original platen 1 is at first positioned so that a chart 20 may be positioned just under a light source 3 and the light from the light source 3 is made transmitted to the center location of the chart 20, reflected on a mirror 4 and mirrors 31, 32 of a Mueller unit 30, and the image of a center location is projected on a CCD 8 via a lens 50. When any magnification is commanded by a magnification command circuit 49 in this state, a variable power is performed by starting a program within a control circuit 45 and by moving the unit 30 and the lens 50 up to the location in accordance with the commanded magnification by driving motors 42 and 43. But, the moving direction of the Mueller unit is determined to get the presence or absence of a pint coincidence and a focusing by performing a focus detection, using the output signal of the picture element in which either one of the focus detection patterns 22a to 22c in accordance with the commanded magnification is projected of the picture elements of the CCD 8, because the obtained target magnification is rough.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image reading apparatus used for, for example, an image scanner or a facsimile, and more particularly to an image reading apparatus and an image reading apparatus for sequentially reading image information of a document conveyed in a predetermined direction by photoelectric conversion elements. The present invention relates to a magnification / focus detection chart used.

[0002]

2. Description of the Related Art A schematic configuration of a conventional image reading apparatus is shown in FIG. In FIG. 5, reference numeral 1 denotes a document table which is conveyed in the direction D1 in the drawing, and a film-shaped document 2 is placed on the document table. The light emitted from the light source 3 arranged above the document table 1 passes through the document 2 when the document table 1 is moved, and then the mirrors 4, 5, 5.
It is reflected in order at 6, and further passes through the lens unit 7 to C
It is guided to an image pickup device (hereinafter referred to as CCD) 8 such as a CD. As a result, the image information of the original 2 is sequentially projected onto the CCD 8. The CCD 8 photoelectrically converts the projected image and sequentially inputs it to a control circuit (not shown). Here, the lens unit 7 is formed by arranging a plurality of lenses 7a, 7b and 7c having different magnifications in a direction orthogonal to the optical axis L, and by inserting any one lens in the optical path, a desired magnification is obtained. To get

[0003]

As described above, in the apparatus of FIG. 5, it is necessary to prepare a plurality of lenses having different magnifications so that a plurality of magnifications can be set, which causes a problem of cost increase.

It is an object of the present invention to provide an image reading apparatus capable of obtaining a plurality of magnifications with a single lens.

[0005]

When the invention of claim 1 is described in association with FIG. 1 showing an embodiment, image information of an original 2 placed on an original table 1 conveyed in a predetermined direction is displayed. It is applied to an image reading device that sequentially reads by the photoelectric conversion element 8. Then, the optical path length changing means 30 driven to change the optical path length from the document table 1 to the photoelectric conversion element 8 and the optical path L between the document table 1 and the image pickup element 8 are interposed. The lens 50 movable in any direction, the variable magnification means (42, 43, 47, 48, 45) for driving the lens 50 and the optical path length changing means 30 to set the commanded magnification, and the output of the photoelectric conversion element 8. Focus detection is performed on the basis of the signal, and focus adjustment means 42, 47, 45 for driving the optical path length changing means 30 to obtain the in-focus state based on the focus detection result are provided. Solve. In particular, the invention of claim 2 provides the photoelectric conversion element 8 with a predetermined focus detection pattern.
The focus adjusting means is configured so as to perform the focus detection by reading with, and a predetermined variable magnification pattern is read by the photoelectric conversion element 8 after the operation of the focus adjusting means, and the commanded magnification is set based on the output signal. Determining means 45 for determining whether or not the commanded magnification is not set
When the determination is made, the control means 45 for activating the zooming means and then again operating the focus adjusting means is further provided. Further, the invention of claim 3 is applied to a scaling chart placed on a document table of a variable-magnification image reading apparatus, and when a commanded magnification is obtained, a predetermined position on the photoelectric conversion element is set. The projected magnification patterns 21a to 21c (FIG. 2) are provided. Further, the invention of claim 4 is applied to a focus detection chart placed on a document table of an image reading apparatus capable of adjusting focus, and focus detection patterns 22a to 22c (FIG. 2) projected on a photoelectric conversion element. Is provided. Note that both the focus detection pattern and the magnification pattern may be provided as in claim 4.

[0006]

(1) Invention of Claim 1 The lens 50 and the optical path length changing means 30 are driven by the zooming means, and the commanded magnification is set by this. Therefore, multiple magnifications can be set with a single lens. In addition, the focus can be adjusted by driving the optical path length changing means 30 independently. (2) The invention of claim 2 After the focus detection by the focus detection pattern, the variable magnification pattern is read by the photoelectric conversion element 8 and it is determined whether or not the commanded magnification is set based on the output signal. To be done. As a result, when it is determined that the commanded magnification is not set, the zooming operation is performed, and then the focus adjusting operation is performed again. (3) Invention of Claim 3 Since the magnification pattern provided on the variable magnification chart is projected at a predetermined position on the photoelectric conversion element of the image reading apparatus when the commanded magnification is obtained, the image reading apparatus In, it is possible to easily determine whether or not the desired magnification is set. (4) Invention of Claim 4 Since the focus detection pattern of the focus detection chart is projected on the photoelectric conversion element, focus adjustment can be easily performed in the image reading device.

Incidentally, in the section of means and action for solving the above problems for explaining the constitution of the present invention, the drawings of the embodiments are used for making the present invention easy to understand. It is not limited to.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS. FIG. 1 shows a schematic configuration of an image reading apparatus according to the present invention, and the same components as those in FIG. 5 are designated by the same reference numerals. The document table 1 is movable by a motor 41 in the direction of D1 in the figure via a drive mechanism (not shown). The document 2 is placed on the upper part of the document table 1, and a film-shaped variable magnification / magnification is provided in front of the document 2.
The focus detection chart 20 (FIG. 2) is placed. The chart 20 will be described in detail later.

Light emitted from the light source 3 passes through the original 2 or the chart 20, is reflected by the mirror 4, and is guided to the mirror unit 30. The mirror unit 30 holds a pair of upper and lower mirrors 31 and 32, and can be moved in the direction D2 in the figure by a rotation of a motor 42 via a drive mechanism (not shown). By moving the mirror unit 30, the document table 1
To the CCD 8 is changed. Reference numeral 50 denotes a lens that can be moved in the direction of the optical axis L by a motor 43 via a drive mechanism (not shown). The light sequentially reflected by the mirrors 31 and 32 passes through the lens 50 and is guided to the CCD 8. .

The photoelectric conversion output of the CCD 8 is A / D converted by the A / D converter 44 and input to the control circuit 45. The control circuit 45 is also connected to the motor drive circuits 46, 47, 48 of the motors 41 to 43 described above,
A magnification command circuit 49 for commanding a magnification according to the operation of an operation member (not shown) is connected. The control circuit 45 outputs a drive signal to the motor drive circuits 42 and 43 according to the commanded magnification and an input signal from the CCD 8, and the mirror unit 3
0 and the lens 50 are driven to change the magnification (magnification), and the mirror unit 30 is independently driven to adjust the focus.

Next, the variable power / focus detection chart 20 described above will be described in detail. This chart 20 is, for example, as shown in FIG. 2A, rectangular magnification patterns 21a, 21b, 21c (shaded areas are shaded) corresponding to three kinds of magnifications A, B, C (A <B <C) on a transparent film member. Black) and the focus detection patterns 22a, 22b, 22c corresponding to the magnification patterns 21a to 21c. Although only the left half is shown in FIG. 2, the pattern is drawn on the right side symmetrically with the left side. When the chart 20 is located directly below the light source 3, the chart 2
An image at a substantially central position (indicated by CL) in the width direction of the pattern on 0 is projected on the CCD 8, and at this time, the magnification patterns 21a to 21a of the pixels 8a (FIG. 2B) of the CCD 8
The output of the pixel 8a at the position E corresponding to 21c becomes low level.

On the other hand, the CCD 8 in the longitudinal direction of the chart
The projection range on the image depends on each magnification. If the magnification A is set, the image of the CL portion in the entire longitudinal direction Ea of the chart 20 is projected on the CCD 8 and the magnifications B and C are set. Chart 20
The images of the CL portion in the central region indicated by Eb and Ec are respectively projected on the CCD 8. When the magnification A is set, a pair of left and right magnification patterns 21a, when the magnification B is set, the same pattern 21b is projected, and when the magnification C is set, the same pattern 21c is projected at the same position on both ends of the CCD in the same size. The position and size are preset. Therefore, no matter which magnification is set, the low-level CCD pixels 8a are the same.

On the other hand, focus detection patterns 22a to 22c
Is composed of a plurality of black line patterns, and focus detection, that is, whether or not focus is achieved, can be detected based on the outputs of CCD pixels at positions corresponding to these focus detection patterns. As this focus detection method,
For example, a contrast method is used, but the details thereof are well known and will not be described here in detail.

Next, the operation of the embodiment will be described with reference to the flowchart of FIG. Initially, the chart 20 is the light source 3
The document table 1 is positioned so as to be positioned directly below the mirror 4. At this time, the light from the light source 3 passes through the CL portion of the chart 20, and then the mirror 4 and the mirror 3 of the mirror unit 30.
1 and 32 are reflected in order, transmitted through the lens 50, and CCD
Guided to 8. That is, the image of the CL portion is the CCD 8
Is projected on.

In this state, the magnification command circuit 49 causes the magnification A
When any one of C to C is commanded, the control circuit 45 in FIG.
In step S1, the control circuit 45 first drives the motors 42 and 43 via the motor drive circuits 47 and 48 to move the mirror unit 30 and the lens 50 to the positions corresponding to the instructed magnification ( Move to (predetermined) and change the magnification. As a result, an approximate target magnification is obtained, but this scaling operation is only a rough adjustment, and does not always mean an accurate command magnification.

Next, in step S2, among the pixels of the CCD 8, focus detection patterns (22a ...
22c) is detected from the output signal of the projected pixel, and as a result, the presence or absence of focus matching and the mirror unit driving direction for obtaining the in-focus state are detected. If it is determined in step S3 that the object is in focus, the process proceeds to step S5, and if it is determined that the object is not in focus, in step S4, the mirror unit 30 is moved to the unit in the detected direction via the motor drive circuit 47. Drive by the amount, then return to step S2. The processing of steps S2 to S4 corresponds to the focus adjustment operation.

In step S5, the signal of each pixel 8a of the CCD 8 is input, and in step S6, C of each pixel 8a is input.
Whether or not the command magnification is set is determined by whether or not the pixels 8a at the predetermined locations at both ends of the CD output low level signals. Here, the above step S
Since the magnification close to the command magnification is set by the variable magnification processing of 1, the magnification pattern other than the command magnification is not projected on both ends of the CCD. Therefore, the command magnification is set only by the judgment in step S5. You can judge whether or not.
If step S6 is affirmed, the procedure proceeds to step S8, and if not, step S7 moves the mirror unit 30 and the lens 5 by a unit amount in a predetermined direction, that is, in a direction in which a pixel signal at a predetermined position becomes a low level, and then step Returning to S2, focus adjustment is performed again.

By the way, in this type of original moving type image reading apparatus, it is necessary to change the moving speed of the original according to the magnification in order to improve the image quality. Therefore, in step S8, the original table according to the set magnification is set. Is calculated by a predetermined calculation formula, and then in step S9, the motor 41 is driven via the motor drive circuit 46 to convey the document table 1 in the direction D1 in the figure at the calculated speed. As a result, the image information of the original 2 is displayed on the mirror 4, the mirror unit 30,
The image is sequentially projected onto the CCD 8 through the lens 50, and the CCD
8 sequentially photoelectrically converts this and inputs it to the control circuit 45.

According to the above, since the magnification is changed by driving the lens 50 and the mirror unit 30, it is possible to change the magnification with a single lens without providing a plurality of lenses having different magnifications as in the conventional case. It is also possible to adjust the focus by driving the optical path length changing means 30 independently.
Further, a desired magnification can be easily set and focus adjustment can be easily performed only by placing the magnification / focus detection chart 20 on the document table 1.

Here, in order to judge whether or not a predetermined magnification is obtained by using the above-mentioned variable magnification chart, it is necessary that the image of the chart is focused on the CCD 8. According to the procedure of FIG. 3 described above, it is determined whether or not the command magnification is set after performing the focus adjustment, and if it is determined that the command magnification is not set, the scaling operation of the unit amount is performed, and then the focus adjustment is performed. Since such an operation is repeatedly performed, the original can be read accurately at a desired magnification and surely in focus.

In the structure of the above embodiment, the CCD 8 controls the photoelectric conversion element, the mirror unit 30 controls the optical path length changing means, and the control circuit 45, the motor drive circuits 47 and 48, and the motors 42 and 43 control the magnification changing means. The circuit 45, the motor drive circuit 47, and the motor 42 form the focus adjustment means, respectively. Further, the control circuit 45 constitutes a judgment means and a control means.

In the above-mentioned chart 20, three kinds of magnification patterns are provided so that three kinds of magnifications can be set. However, for example, as shown in FIG. It is possible to set multiple types of magnifications only with compatible ones). In this case, since which pixel 8a of the CCD 8 the magnification pattern 21 'is projected on depends on the magnification, the magnification is determined by determining the position and number of the pixels 8a on which the magnification pattern 21' is projected. It can be determined whether or not it has been set. Although the magnification pattern is painted black, conversely, the same effect can be obtained by making the magnification pattern transparent and painting the peripheral portion black. Furthermore, although an example in which each magnification pattern and focus detection pattern are provided symmetrically has been shown, each pattern may be only one. The number of patterns, that is, the settable magnification may be 4 or more, and the shape of each pattern is not limited to the embodiment. Furthermore, although an example in which both the magnification pattern and the focus detection pattern are provided is shown, only one of them may be provided. Furthermore, the document reading type image reading apparatus has been described, but the present invention can be applied to a document reflecting type image reading apparatus.

[0023]

According to the image reading apparatus of the first aspect, the commanded magnification is set by driving the lens and the optical path length changing means. Therefore, a plurality of lenses having different magnifications are prepared as in the conventional case. It is not necessary to do so, and the cost can be reduced. Further, since the focus is adjusted by independently driving the optical path length changing means which is a part of the variable power mechanism,
It is not necessary to newly provide an optical member for focus adjustment, and the cost can be further reduced. Particularly, according to the second aspect of the present invention, it is determined whether or not the command magnification is set after performing the focus adjustment, and if it is determined that the command magnification is not set, the unit variable magnification operation is performed, and then the focus adjustment is performed. Since this is done, the original can be read accurately at the desired magnification and surely in focus. According to the scaling chart of claim 3, a predetermined pattern is projected at a predetermined position on the photoelectric conversion element when the commanded magnification is obtained, so that a desired magnification can be obtained with a simple configuration. Can be set easily and surely. According to the focus adjustment chart of claim 4,
Since the focus detection pattern is projected on the photoelectric conversion element, the focus adjustment can be performed easily and reliably with a simple configuration.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing an embodiment of an image reading apparatus according to the present invention.

FIG. 2A is a plan view showing the configuration of a magnification / focus adjustment chart, and FIG. 2B is a CCD according to the chart pattern.
It is a figure which shows a signal level.

FIG. 3 is a flowchart illustrating the operation of the embodiment.

FIG. 4 is a diagram showing a modified example of the chart.

FIG. 5 is a schematic configuration diagram of a conventional image reading apparatus.

[Explanation of symbols]

 1 Document Plate 2 Document 3 Light Source 4 Mirror 8 CCD 20 Magnification / Focus Adjustment Chart 21a-21c Magnification Pattern 22a-22c Focus Detection Pattern 30 Mirror Unit 41, 41, 43 Motor 45 Control Circuit 46, 47, 48 Motor Drive Circuit 49 Magnification command circuit 50 Lens

Claims (5)

[Claims] 1. An image reading apparatus for sequentially reading image information of a document placed on a document table conveyed in a predetermined direction by a photoelectric conversion element, wherein the image reading device is driven to change an optical path length from the document table to the photoelectric conversion element. Optical path length changing means, a lens interposed in the optical path between the document table and the image pickup device, and movable in the optical axis direction thereof, the lens and the optical path length changing means for setting a commanded magnification. Zooming means for driving the means, focus detection means for performing focus detection based on the output signal of the photoelectric conversion element, and focus adjustment means for driving the optical path length changing means to obtain a focused state based on the focus detection result. An image reading apparatus comprising: 2. The focus adjusting means is configured to perform a focus detection by reading a predetermined focus detection pattern with a photoelectric conversion element, and a predetermined scaling pattern with a photoelectric conversion element after the focus adjustment means is operated. When the determination means determines that the read magnification is set and the commanded magnification is set based on the output signal, and that the commanded magnification is not set,
2. The image reading apparatus according to claim 1, further comprising control means for activating the zooming means and then reactivating the focus adjusting means. 3. A variable-magnification chart placed on a document table of a variable-magnification image reading apparatus, which projects onto a predetermined position on a photoelectric conversion element when a commanded magnification is obtained. A variable magnification chart characterized in that a magnification pattern is provided. 4. A focus detection chart placed on a document table of a focus adjustable image reading apparatus, wherein a focus detection pattern projected onto a photoelectric conversion element is provided. Focus detection chart. 5. The focus detection chart according to claim 4, further comprising a magnification pattern projected on a predetermined position on the photoelectric conversion element when the commanded magnification is obtained.